In a combustion chamber of an internal combustion engine, an air-fuel mixture of air and fuel is ignited in a compressed state. It is known that a compression ratio when compressing the air-fuel mixture has an effect on output torque and an amount of fuel consumption. It is possible to raise the compression ratio so as to increase the torque or so as to reduce the amount of fuel consumption. On the other hand, it is known that if making the compression ratio too high, knocking or other abnormal combustion phenomena will occur. In the prior art, there has therefore been known an internal combustion engine which is provided with a various compression ratio mechanism which enables the compression ratio to be changed during the operating period.
Japanese Patent Publication No. 2008-075602A discloses a variable compression ratio mechanism which can change relative positions of a crankcase and a cylinder block in a cylinder axial direction so as to change the volumes of combustion chambers when pistons are positioned at compression top dead center.
Further, Japanese Patent Publication No. 60-22030A discloses a variable compression ratio engine in which a cylinder block is joined to a crankcase or cylinder head by a shape memory alloy. It discloses that this shape memory alloy is formed so as to contract in a cylinder axial direction at a low temperature side and to expand at a high temperature side.
Japanese Patent Publication No. 2008-045443A discloses an internal combustion engine which is provided with a variable compression ratio mechanism which makes a cylinder block move relative to a crankcase wherein the cylinder block and the crankcase have a spring mechanism provided between them. This spring mechanism biases the cylinder block and the crankcase in a direction making them approach each other.
Japanese Patent Publication No. 2011-153597A discloses an internal combustion engine which is provided with a variable compression ratio mechanism which makes a cylinder block move relative to a crankcase wherein a water jacket is formed which runs cooling water to the inside of a cylinder head.
Japanese Patent Publication No. 2011-144789A discloses an internal combustion engine which is provided with a variable compression ratio mechanism which makes a cylinder block move relative to a crankcase wherein the cylinder block and the crankcase have a ring-shaped seal member provided between them. This discloses that the seal member is formed so as to cover the clearance between the cylinder block and the crankcase over the entire circumference of the internal combustion engine.
Further, Japanese Patent Publication No. 2010-106710A discloses a cylinder liner which is provided in a cylinder block and which slides with a piston. This cylinder liner has a sliding surface part which allows the piston to slide and a nonsliding surface part which does not contact the piston. This discloses that the sliding surface part is comprised of an inner wall surface of a cylindrical member, while the nonsliding surface part is comprised of the end part of the cylindrical member which is gradually increased in diameter from the inner wall surface outward in the radial direction to form an inclined surface.